Highly homogenous zeolite precursors

ABSTRACT

Described herein are methods and compositions for zeolite synthesis. The methods and compositions involve modifying a colloidal silica sol with a metal compound and in the presence of a structure directing agent, followed by heating to form a zeolite. The methods and compositions result in rapid zeolite formation, even at reduced concentrations of structure directing agent.

BACKGROUND OF THE INVENTION

The invention relates to compositions, methods, and apparatuses forimproving the manufacture of zeolites. In particular it relates tocompositions and their use as precursors to zeolite manufacture.

Zeolites are microporous, metalosilicate (especially aluminosilicate)minerals commonly used as commercial adsorbents and catalysts. WhileZeolites occur naturally they are also produced industrially on a largescale. Zeolite mineral is characterized as microporous because theirconstituent silicon, oxygen, and metal/aluminum atoms are arranged intovarious possible ring configurations which are positioned in a seriessuch that the series of rings define channels passing through themineral. The specific number and ratio of types of atoms in a given ringdetermines the width of the channels. As a result, different numberedrings can result in channel width which varies such that they arecapable of accommodating only one or some of specific ions/cations suchas one or more of Na⁺, K⁺, Ca²⁺, Mg²⁺ and others. As a result zeolitesare often used as and referred to as molecular sieves.

Because of their unique structure and their ion-specific affinity,zeolites possess a number of properties that are desirable for a widerange of industrial and commercial uses. Such uses include but are notlimited to: ion-exchange beds, water purification, water softening,catalysts, sorbents, gas separation, oxygen gas generation,petrochemical catalysts, Lewis acid catalysts, catalytic crackingcatalysts, nuclear-radioactive material substrates, hygroscopic heatabsorbers, detergents, asphalt-concrete substrates, gemstones, blooddotting agents, potassium releasing fertilizer, agricultural waterreleasing agents, and aquarium filters.

Unfortunately naturally occurring zeolites do not have channels ofuniform size, orientation, or shape, and the channels are oftencontaminated by other unwanted minerals, metals, quartz, or otherzeolites. As a result, there is clear utility in novel techniques ofzeolite synthesis and precursors thereof that facilitate the specificproperties most beneficial to a specific uses of zeolite.

BRIEF SUMMARY OF THE INVENTION

To satisfy the long-felt but unsolved needs identified above, at leastone embodiment of the invention is directed towards a method of formingzeolites. The method comprises the steps of modifiying a colloidalsilica sol with a metal compound and in the presence of an SDA to atemperature of at least 100° C. for a time period of at least 0.1 hoursand no more than 10 hours.

The metal may be one item selected from the group consisting of: analkali metal, an alkaline earth metal, a 1st row transition metal, a 2ndrow transition metal, a lanthanide, aluminum, cerium, titanium, tin,zirconium, zinc, copper, nickel, molybdenum, iron, rhenium, vanadium,boron, and any combination thereof. The SDA may be one item selectedfrom the group consisting of: tetramethylammonium hydroxide,tetrapropylammonium hydroxide, tetraethylammonium hydroxide,tetrabutylammonium hydroxide, tetrahexylammonium hydroxide,tetraoctylammonium hydroxide, tributylmethylammonium hydroxide,triethylmethylammonium hydroxide, trimethylphenylammonium hydroxide,methyltripropylammonium hydroxide, dodecyltrimethylammonium hydroxide,hexadecyltrimethylammonium hydroxide, dimethyldodecylethylammoniumhydroxide, diethyldimethylammonium hydroxide, and any combinationthereof. The SDA may be in the form of one item selected from the groupconsisting of: a bromide, a chloride, an ammonium salt, a alkylammoniumhydroxide, and any combination thereof. The colloid may have an S-Valuewhich is at least 20% lower than if the same amount of silica and metalwere present in a non-doped form. The colloidal silica is modified byincorporating the metal in the framework or on the surface of thesilica. The doped metal may be a coating at least in part surrounding adroplet of the colloidal silica. The time period may be no more than 4hours and the crystallinity is in excess of 80%. The resulting zeolitemay have a higher crystallinity than an otherwise identical processdiffering only in that the metal and silicon were in a non-modifiedform. The resulting zeolite may have a higher crystallinity than anotherwise identical process differing only in that at least 10% more SDAwas used. The modification of colloidal silica may occur at atemperature of 70-90 C and the metal and silicon were in a non-modifiedform. The resulting zeolite may have a higher crystallinity than anotherwise identical process differing only in that the metal and siliconwere in a non-colloidal form.

Additional features and advantages are described herein, and will beapparent from, the following Detailed Description.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of the invention is hereafter described withspecific reference being made to the drawings in which:

FIG. 1 is an electron microscope (SEM) photograph of a beta type zeolitecrystal formed from modified precursors in a relatively short period oftime with a relatively low level of SDA.

FIG. 2 is an electron microscope (SEM) photograph of a chabazite typezeolite crystal formed from modified precursors in a relatively shortperiod of time with a relatively low level of SDA.

FIG. 3 is an NMR spectrum of the modified silica precursors indicatingthat the Al species in the precursor are mainly in a tetrahedral andoctahedral coordination.

FIG. 4 is an illustration of a Keggin type arrangement containingtetrahedral and octahedral components.

For the purposes of this disclosure, like reference numerals in thefigures shall refer to like features unless otherwise indicated. Thedrawings are only an exemplification of the principles of the inventionand are not intended to limit the invention to the particularembodiments illustrated.

DETAILED DESCRIPTION OF THE INVENTION

The following definitions are provided to determine how terms used inthis application, and in particular how the claims, are to be construed.The organization of the definitions is for convenience only and is notintended to limit any of the definitions to any particular category.

“Chemical Shift” also referred to as δ, means the variation of resonantfrequency of a nucleus relative to a standard in a magnetic field whichfunctions as a diagnostic of the structure of a composition of mattercontaining that nucleus, it is a function of properties of the nucleusincluding: magnetic moment (nuclear spin), local magnetic fields inducedby currents of electrons in the molecular orbitals, and local geometry(binding partners, bond lengths, angles between bonds), it is morefurther described in the article NMR Nomenclature. Nuclear SpinProperties and Conventions for Chemical Shifts by Robin Harris et al,Pure Applied Chemistry Vol. 73 No. 11, pp. 1795-1818 (2001), and thereference: 5.2 Chemical Shift, by

Hans I Reich, University of Wisconsin. Web. October, 20 (2015),<http://www.chem.wisc.edu/ereas/reich/nmr/05-hmr-02-delta.htm>, unlessotherwise stated in this application a measured chemical shift isreferenced to the measured signal of tetramethylsilane.

“SAR” means silica to aluminum ratio it includes the ratio betweenalumina and silica molecules.

“SDA” means structure directing agent, a material which positions theconstituent Si and Al atoms of a zeolite precursor to assume a specificdesired configuration, usually a particular sized/shaped ringarrangement, ideally SDA's are also easy to remove from the resultingzeolite formation.

“Colloid” or “Colloidal System” means a substance containing ultra-smallparticles substantially evenly dispersed throughout another substance,the colloid consists of two separate phases: a dispersed phase (or solor internal phase) and a continuous phase (or dispersion medium) withinwhich the dispersed phase particles are dispersed, the dispersed phaseparticles may be solid, liquid, or gas, the dispersed-phase particleshave a diameter of between approximately 1 and 1,000,000 nanometers, thedispersed-phase particles or droplets are affected largely by thesurface chemistry present in the colloid, thus a colloid encompassesboth the dispersed phase and the continuous phase.

“Stable” means that the solid phase of the colloid is present, dispersedthroughout the medium, and stable throughout this entire pH range witheffectively no precipitate.

“Modifying”or “Modified Precursors” refers to a process of physicallycontacting a silicon bearing material such as silicic acid or colloidalsilica with one or more molecules of a metal component dispersed atleast in part within or around the framework of a colloidal silica sol,it may include doping sols with the metal component.

“Heel” refers to an aqueous basic solution in the doping process thatmay at least includes a quaternary amine or an alkaline agent.

“Colloidal Silica” means a colloid in which the primary dispersed-phaseparticles comprise silicon containing molecules, this definitionincludes the full teachings of the reference book: The Chemistry ofSilica: Solubility, Polymerization, Colloid and Surface Properties andBiochemistry of Silica, by Ralph K. Iler, John Wiley and Sons, Inc.,(1979) (hereinafter “Chemistry-Silica”) generally and also in particularpages 312-599, in general when the particles have a diameter of above100 nm they are referred to as sols, aquasols, or nanoparticles.

“Consisting Essentially of” means that the methods and compositions mayinclude additional steps, components, ingredients or the like, but onlyif the additional steps, components and/or ingredients do not materiallyalter the basic and novel characteristics of the claimed methods andcompositions.

“Droplet” means a mass of dispersed phase matter surrounded bycontinuous phase liquid, it may be suspended solid or a dispersedliquid.

“Microparticle” means a dispersed-phase particle of a colloidal system,generally microparticle refers to particles that have a diameter ofbetween 1 nm and 100 nm which are too small to see by the naked eyebecause they are smaller than the wavelength of visible light.

“Particle Size” means the surface area of a single droplet.

“S-Value” means the measure of the degree of microaggregation ofcolloidal materials, it can be obtained from measurements of viscosityof the colloidal system and is often related to the performance of thecolloidal end product, its exact metes and bounds and protocols formeasuring it are elucidated in the book Chemistry-Silica.

“Silanol” means a functional group on a silicon bearing molecule withthe connectivity of Si—O—H.

“Solids %” means the portion of an aqueous system by weight that issilica bearing particles of the continuous phase.

In the event that the above definitions or a description statedelsewhere in this application is inconsistent with a meaning (explicitor implicit) which is commonly used, in a dictionary, or stated in asource incorporated by reference into this application, the applicationand the claim terms in particular are understood to be construedaccording to the definition or description in this application, and notaccording to the common definition, dictionary definition, or thedefinition that was incorporated by reference. In light of the above, inthe event that a term can only be understood if it is construed by adictionary, if the term is defined by the Kirk-Othmer Encyclopedia ofChemical Technology, 5th Edition, (2005), (Published by Wiley, John &Sons, Inc.) this definition shall control how the term is to be definedin the claims. All illustrated chemical structures also include allpossible stereoisomer alternatives.

At least one embodiment of the invention is directed towards modifiedzeolite precursors and a method of producing zeolite from suchprecursors. The modified precursors are characterized as having a highlyhomogeneous distribution of constituents such that specific zeolites canbe formed in relatively short periods of time.

As described in US Patent Application 2013/0052125 and 2005/0234136, andU.S. Pat. Nos. 8,106,229, 8,845,991, 5,026,532, 5,863,516, 8,658,127,zeolite can be synthesized through the combination and nucleation(potentially under heating) of precursors including: a silica source, analumina source, and a structure directing agent. Synthesis of ZeoliteBeta Using Silica Gel as a Source of SiO ₂, by R N Bhat et al., Journalof Chem. Tech. And Biotech., Vol. 48, pp. 453-466 (1990) demonstratesthat reaction times of: 4, 5, 6, and 8 days resulted in crystallinityvalues of 20%, 30%, 60% and 100% respectively for zeolites having aspecific desired SAR.

In contrast the use of modified precursors in zeolite synthesis produceshigh crystallinity values in short reaction times. While the exactprocess of zeolite formation from precursors is not preciselyunderstood, the scientific paper The hydrothermal synthesis of zeolite:Precursors, intermediates and reaction mechanism, by C S Cundy et al,Microporous and Mesoporous Materials, Vol. 82, pp. 1-78 (2005) explainsthat the prior art methods involve a process including a randomlyarranged amorphous gel transitioning into an increasingly orderedequilibrated gel which eventually undergoes nucleation into crystallinezeolite. Without being limited by a particular theory or design of theinvention or of the scope afforded in construing the claims, it isbelieved that the prenucleation arrangements of modified precursorsaffect this transition to reduce the required crystallization time.

In at least one embodiment the nucleation is performed according to anyone or any combination of methods described in any one, some, or all, ofthe prior art cited herein and incorporated by reference into thisapplication, improved by the addition of an arrangement of modifiedprecursors.

In at least one embodiment the arrangement of modified precursors isachieved through the use of metal (such as aluminum) doped colloidalsilica sols. The method can include preparing a silicic acid and mixinga known proportion of the metal oxide dispersion to form a silica andaluminum percursors. Subsequently, combining the metal modified silicicacid and the basic heel solution at room temperature forms one or morecolloidal silica-modified metal oxide particles. In a metal modifiedcolloidal silica sol the zeolite precursors are highly and evenlydistributed throughout a solvent. In an embodiment, this combination isperformed at temperatures ranging from 70-90° C. resulting in asegregation of aluminum in the form of Aluminum hydroxide. Moreover,because specific zeolite properties are highly dependent on the ratio ofalumina to silica and in particular to the various atomic coordinationthat the proportions of the two (as well as oxygen) facilitate,pre-bonding aluminum in the silica network allows for the rapidformation of zeolite species that are otherwise difficult or possiblyimpossible to form if subject to the slow prior art kinetics. Inaddition, modifying colloidal silica results in some of theSilicon-Oxygen-Aluminum bonds pre-existing the reaction process givingthe overall reaction a time saving head-start.

In another embodiment, the homogenous arrangement of precursors isachieved through the use of aluminum coated silica sols. Colloidalsilica, for example, has been coated with various metallic compounds asdisclosed in U.S. Pat. Nos. 3,252,917, 3,745,126, and also in the bookChemistry-Silica (generally and in particular pages 410-411). Coatedcolloidal silica allows for pre-bonding the aluminum precursors on thesurface of colloidal particles dispersed in an aqueous medium whilekeeping the silicon molecules bound with each other. This arrangement ofprecursors favors crystallization kinetics of zeolites where aluminum isa limiting reactant or silicon is released slowly.

In both previous embodiments, it is believed that the pre-bonded,non-agglomerated nature of the colloidal precursors provides for anadded homogeneity conducive to faster zeolite crystallization kinetics.

The use of metal (such as aluminum) modified colloidal silica as a meansof increasing reaction kinetics in an unexpected result which isopposite the teachings of the prior art. The prior art teaches to startwith a “clear” solution containing one or the other of the silica oraluminum and to add the other slowly in a gradual drop-wise manner lesta viscous agglomerated gel result that would greatly slow down/impairthe zeolite formation (See Scientific Papers Formation of colloidalmolecular sieves: influences of silica precursor, by S Mintova et al,Colloids and Surfaces, Vol. 207 pp. 153-157 (2003)) and Effects of thesilica sources on the crystallinity of nanosized ZSM-5 zeolite, by R MMohamed et al, Microporous and Mesoporous Materials, Vol. 79, pp. 7-12(2005). In contrast the invention accomplishes the rapid reactionkinetics by dosing much or all of the precursors at once or in acontrolled manner, the exact opposite of the teachings of the prior art.

In at least one embodiment the modification of colloidal silica ischaracterized as the metal (such as aluminum) molecules being embeddedwithin the silica network of the sol.

In at least one embodiment the modification of colloidal silica ischaracterized as the metal (such as aluminum) molecules forming bondswith silicon at the outer surface of the particles. This may result in apartial or complete enclosing of the metal particles.

In at least one embodiment the resulting zeolite achieves acrystallinity value of between 75% and 100% within a time period of nomore than 4 hours (preferably no more than 3 hours) or even less.

In at least one embodiment the modified colloidal silica results in thesame crystalline properties as a non-modified precursor that makes useof at least 10% more SDA.

In at least one embodiment the silica precursor is in the form ofcolloidal particles or molecular silicic acid. Representative silicicacid may be created by deionization of Na-silicate with a cationicresin. Silicic acid is the general name for a family of chemicalcompounds containing the element silicon attached to oxide and hydroxylgroups. This family of compounds have the general formula[SiO_(x)(OH)_(4−2x)]_(n). Colloidal particles may be synthesized byadding a silicic acid solution to a reaction vessel that includes analkaline aqueous heel solution. Upon addition in the heel, the silicicacid polymerizes, SiO₂ nucleate and silica particles grow in thesolution. The growth rate and final size depends on the feed rate, pHand temperature of polymerization.

In at least one embodiment the colloidal silica is modified withaluminum and/or one or more other metal compounds. The metal compoundmay be an aqueous metal compound. The metal may include any suitablematerial and be derived from any suitable material including metal saltsthat are soluble or substantially soluble in an aqueous solution. Themetal may include an alkali metal, an alkaline earth metal, a 1st rowtransition metal, a 2nd row transition metal, a lanthanide, an actinide,and combinations thereof. Preferred metal components include but are notlimited to one or more of: aluminum, cerium, titanium, tin, zirconium,zinc, copper, nickel, molybdenum, iron, rhenium, vanadium, boron, thelike and any combination thereof.

In at least one embodiment the precursor may result in part betweencontact between silica and a metal salt. The cationic (or whenappropriate other) portions of such a salt may comprise one or more ofan: acetate, carbonate, chloride, bromide, iodide, citrate, cyanide,fluoride, nitrate, nitrite, phosphate, phosphoric acid, sulfate,nitride, nitrite, chlorate, perchlorate, sulfide, borate, chromate,phosphide, sulfite, bromate, hydroxide, ammonium, and any combinationthereof.

The metal compound may be added to the silicic acid prior to thepolymerization reaction, co-fed with the silicic acid into the aqueousalkaline heel or added to the heel prior to feeding the silicic acid.During particle formation, the OFF present in the heel catalyzes thecopolymerization of the cationic metal component and silicate (SiO⁴⁻)from the silicic acid. This produces a colloid with the metal dispersedwithin the silicate (i.e., incorporated into the particle framework),such as having a homogenous distribution of the metal componentthroughout the entire solid phase of the precursors. It is believed thatthe dispersion and loading of the metal is obtained as thecopolymerization forms a metal-silicate lattice throughout themicrostructure of the solid phase. Alternatively, the metal compound canbe added onto the surface of colloidal silica particles. The process formaking the modified composition comprises intimately and homogeneouslycoating the metal compound onto the surface of the colloidal amorphoussilica so as to establish a stable chemical bond between the metalcompound and the silica. This can be done by preparing a colloidaldispersion of silica and contacting this dispersion simultaneously witha solution containing a soluble source of the metal ion. For example, asilica sol having a concentration between 5% and 40% SiO₂ can be coatedwith a metal compound by slowly adding a soluble compound of the metalunder constant agitation. This process can be continued for as long aperiod of time as is required to build up the desired SAR as a coatingon the colloidal amorphous silica sols.

Referring now to FIG. 3, a comparison of NMR spectra between the priorart precursors and the modified precursors is shown. The modifiedprecursor displays different properties compared to the prior artprecursor. While FIG. 3 specifically displays an aluminum-usingprecursor, this is merely representative and it is understood that theprinciple equally applies to other metals as well. The prior artprecursor comprises a variety of spectra signals for many differentspecies of metal (alumina) such as Al(OH)⁻⁴ and Al(H₂O)⁺³ ₆ as well asthe tetrahedral and octahedral components of Keggin-type Al₁₃O₄(OH)³⁺₂₈. In contrast the modified precursor is largely limited to tetrahedraland octahedral species. In at least one embodiment no less than anamount of up to, equal, or more than 90% of the metal species in thecolloidal system is in the form of a tetrahedral or octahedralstructured species.

Also seen in the spectra in FIG. 3 is the fact that the tetrahedral andoctahedral peaks have undergone a rightward or upfield chemical shift.This indicates that the metal species are experiencing a lesselectronegative environment. This is probably due to the greater amountof silica-metal interactions taking place which shield the tetrahedraland octahedral species from interacting with negative ions present inthe colloidal system such as chlorides, halogens, salt cations, and/orother cations. Also, as more of the metal is in the form of tetrahedraland octahedral arrangement, they are not in the form of other aluminaspecies more prone to interactions with cations in the continuous phase.The ratio of measured signals for tetrahedral to octahedral species alsochanged from 1:3 in the prior art precursor to 1:1 in the modifiedprecursor.

In at least one embodiment an amount of up to, equal, or more than 90%of the metal species in the colloidal system is sufficiently shieldedfrom cations in the colloidal system such that it manifests at least upto or equal to a chemical shift (δ) of at least 5 ppm relative to theprior art precursor.

In at least one embodiment an amount of up to, equal, or more than 90%of the metal species in the colloidal system is in the form of a Kegginstructure. As described in the article Studies on the mechanism ofhydrolysis and polymerization of aluminum salts in aqueous solution:correlations between the “Core-links” model and “Cage-like” Keggin-Al ₁₃model, by Shuping Bi et al, Coordination Chemistry Reviews, Vol. 248,pp. 441-445 (2004), polynuclear Al can exist in a form comprising an Alcore (tetrahedral or octahedral) “caged” by tetrahedral or octahedral Alunits. FIG. 4 illustrates such a Keggin structure of a zeolite. BecauseFIG. 3 makes clear that the modified sols comprise tetrahedral andoctahedral units and lack most/all of the other species it appears to bea Keggin structure. In at least one embodiment the Keggin structurecomprises 1-40 tetrahedral units and 1-40 octahedral units. In at leastone embodiment the metal is aluminum and the Keggin structure issubstantially in the form of Al₁₃O₄(OH)³⁺ ₂₈. In at least one embodimentthe metal is aluminum and the Keggin structure is substantially in theform of [Al₁₃O₄(OH)₂₄(H₂O)₁₂]⁷⁺. In at least one embodiment the metal isaluminum in the form of a Keggin-Al₁₃ arrangement. In at least oneembodiment there is a single tetrahedral arrangement at the core of theKeggin structure and there are numerous octohedral arrangementssurrounding the core.

In at least one embodiment an amount of up to, equal, or more than 90%of the metal species in the colloidal system is in the form of a freestanding molecular arrangement. In prior art precursors, a metal salt ismixed with colloidal silica which remains dispersed only in a pH narrowrange. The two become mixed by changing the pH and precipitating out amixture of silica and metal. This however results in the metalprecipitate being an agglomeration of multiple molecules. In contrast,with modified precursors, each metal particle is in the form of only 1or a few molecules which are out of direct contact with the balance ofthe metal in the colloidal system. In at least one embodiment themolecule is a free standing (relative to other metal particles not tosilica because it is in contact with the sol) Keggin structure of metal.In at least one embodiment the molecule is a mass comprising metal whichhas a cross section smaller than one of: 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4.4.5, 5, or 5.5 nm. These masses are in physical contact with the soleither embedded within its bulk or in part or entirely along the sol'ssurface.

In at least one embodiment, the metal assumes a polyoxometalatestructure other than a Keggin structure. This includes geometricarrangements which in addition to possibly including tetrahedral andoctahedral arrangements may also possibly include those such as one ormore of: linear, trigonal planar, tetrahedral, trigonal bipyramidal,octahedral, bent, trigonal pyramidal, see-saw, square pyramidal,T-shaped, square planar, and any combination thereof. In at least oneembodiment, the polyoxometalate structure comprises 1-500 of any one,some, or all of the geometric arrangements. In at least one embodimentthe metal component comprises 1-40 tetrahedral units and 1-40 octahedralunits but is not a “caged” Keggin structure.

In at least one embodiment the ratio of doped material to silica can beeasily controlled by mixing the proper amount of precursors. Thisability provides an easy path to make high SAR zeolites. High SARzeolites are sought for their high thermal stability, acid resistant andenhance catalysis selectivity in petrochemical processes. Nonlimitingexamples of SAR ranges easily attainable with the technology include:18-40 for chabazite and 62.5-600 for beta.

In at least one embodiment an SDA precursor is used. The efficientsynthesis of sophisticated zeolite-based compositions often requires theuse of SDAs. Preferably, the SDA component is a quaternary amine thatforms an alkaline solution when dispersed in water, such as quaternaryammonium hydroxides. In addition, it is further preferred that thequaternary amine includes a tetraalkyl ammonium ion wherein each alkylgroup has a carbon chain length of 1 to 10, the alkyl groups being thesame or different.

Nonlimiting examples of quaternary amines suitable for use as thestabilizer include one or more of: tetramethylammonium hydroxide(TMAOH), tetrapropylammonium hydroxide (TPAOH), tetraethylammoniumhydroxide (TEAOH), tetrabutylammonium hydroxide (TBAOH),tetrahexylammonium hydroxide, tetraoctylammonium hydroxide,tributylmethylammonium hydroxide, triethylmethylammonium hydroxide,trimethylphenylammonium hydroxide, methyltripropylammonium hydroxide,dodecyltrimethylammonium hydroxide, hexadecyltrimethylammoniumhydroxide, dimethyldodecylethylammonium hydroxide,diethyldimethylammonium hydroxide, the like and any combinationsthereof. Also, any combination of the bromide and chloride forms of theabove mentioned ammonium salts can be used by passing through ahydroxide (anion)-exchange column to produce the alkylammonium hydroxidematerials. Alternatively, the SDA can be eliminated by a careful controlof the nucleation kinetics to create hydrogel systems.

In at least one embodiment the precursors include an alkali metalhydroxide and/or an alkaline earth metal hydroxide such as one or moreof: the hydroxide of sodium, potassium, lithium, cesium, rubidium,calcium and magnesium.

In at least one embodiment the alkali metal hydroxide is omitted.

In at least one embodiment the nucleation reaction is conducted withoutan alkali metal hydroxide but under basic conditions (such as with theuse of a hydroxide source).

In at least one embodiment the basic conditions are achieved by the useof an SDA which also doubles as a hydroxide source.

In at least one embodiment the modified colloidal silica undergoesheating for a time period of between 1 minute and up to 10 days. For atleast a portion of the time the heating is at a temperature of at least100° F.

In at least one embodiment the resulting zeolite is one or more of:gonnardite, natrolite, mesolite, paranatrolite, scolecite,tetranatrolite, edingtonite, kalborsite, thomsonite, analcime, leucite,pollucite, wairakite, yugawaralite, goosecreekite, montesommaite,harmotome, phillipsite, amicite, gismondine, garronite, gobbinsite,boggsite, merlinoite, mazzite, paulingite, perlialite, chabazite,herschelite, willhendersonite, faujasite, maricopaite, mordenite,offretite, wenkite, bellbergite, bikitaite, erionite, ferrierite,gmelinite, dachiardite, epistilbite, clinoptilolite, heulandite,stilbite, barrerite, stellerite, brewsterite, cowlesite, pentasil,tschernichite, and beta.

In at least one embodiment the precursors are so homogenous that theentirety of the SAR distribution is contained within a volume of no morethan 200 nm³. For example, all or substantially or essentially all ofthe colloidal sols are within such a small volume and all of thealuminum, oxygen, and silicon are within those sols so all of theprecursors are within such a small volume. In at least one embodimentthe precursors are so homogenous that the entirety of the SARdistribution is essentially homogenous at a size of from less than or upto 50 nm³ up to 1000 nm³ or greater.

EXAMPLES

The foregoing may be better understood by reference to the followingexamples, which are presented for purposes of illustration and are notintended to limit the scope of the invention. In particular, theexamples demonstrate representative examples of principles innate to theinvention and these principles are not strictly limited to the specificcondition recited in these examples. As a result it should be understoodthat the invention encompasses various changes and modifications to theexamples described herein and such changes and modifications can be madewithout departing from the spirit and scope of the invention and withoutdiminishing its intended advantages. It is therefore intended that suchchanges and modifications be covered by the appended claims.

A number of samples were run involving the conversion of precursors intochabazite or beta type zeolite. For all of the samples the precursorsincluded a silica source and an SDA. The samples had different amountsof SDA and were heated in a reactor for different amounts of time and atdifferent temperatures. The colloidal silica was modified either byincorporating aluminum into the framework or on the surface of theparticles.

The crystallinity of the reaction products were measured using a PowderX-ray diffraction (XRD) measurements operating at 45 kV and 40 mA, andusing Cu Kα radiation (λ=0.1542 nm). The morphology of the samples wasstudied by scanning electron microscopy (SEM) using a Hitachi S3000Nmicroscope. Textural properties were determined by N2 adsorptionisotherms measured at 77 K with a Quantachrome ASIQWin. The modifiedprecursors all had the NMR spectra of FIG. 3.

The results show that by modifying colloidal silica in the bulk(embedded within the sol/particle) or on the surface of the particles a90-100% crystalline product could be achieved within a much shorter timeperiod than taught by the prior art. For a particular Al: Si ratio andtemperature combination that required 40 hours to achieve substantially100% crystallinity, the use of coated colloidal silica only required 3hours and embedded colloidal silica required only 6 hours. Moreover thiswas achieved using much less molar SDA (0.04 instead of 0.07). Thus itis clear that the use of modified colloidal silica results in vastlyfaster reaction kinetics. Tables 1 and 2 summarize the results.

TABLE 1 Chabazite Zeolite Nucleation Results Precursor CrystallizationSDA: # Arrangement T (° C.)/t (hrs) Precursor Type Si Crystallinity % 1mesoporous 170/40 Al chlorohydrate 0.07 Chabazite, 38 agglomeration bulkmodified silica 2 dispersed 170/24 Al chlorohydrate 0.04 Chabazite, 78modified colloid bulk modified silica 3 dispersed 170/12 Alchlorohydrate 0.04 Chabazite, 73 modified colloid bulk modified silica 4dispersed 170/6  Al chlorohydrate 0.04 Chabazite, 71 modified colloidbulk modified silica 5 dispersed 170/3  Al chlorohydrate 0.04 Chabazite,54 modified colloid bulk modified silica 6 dispersed 170/40 Alchlorohydrate 0.03 Chabazite, 76 modified colloid bulk modified silica 7dispersed 170/40 Al acetate dibasic 0.04 Chabazite, 65 modified colloidbulk modified silica 8 dispersed 170/40 Al Sulfate bulk 0.04 Chabazite,67 modified colloid modified silica 9 dispersed 170/40 Al Lactate bulk0.04 Chabazite, 63 modified colloid modified silica 10 dispersed 170/40Al chlorohydrate 0.04 Chabazite, 89 modified colloid bulk modifiedsilica 11 dispersed 170/40 Al acetate surface 0.07 Chabazite, 100modified colloid modified silica 12 dispersed 170/20 Al chlorohydrate0.07 Chabazite, 61 modified colloid surface modified silica 13mesoporous 170/40 Al chlorohydrate 0.04 Amorphous agglomeration bulkmodified silica

Table 1 demonstrates the superiority of the invention over themesoporous precursor process described in U.S. Pat. No. 8,658,127. For agiven sample of silica modified with Al chlorohydrate and reacted in thepresence of an adamantylammonium hydroxide SDA, samples #1 and #13describe what occurs when these precursors are in the form of the priorart mesoporous agglomeration when the reaction is begun. Sample 13 showsthat with a low amount of SDA at 170° C. after 40 hours a zeolite doesnot form. Sample 1 shows that with a high amount of SDA a low quality(low crystallinity %) chabazite zeolite forms.

In contrast samples 2, 3, 4, 5, and 6 shows that with a modifiedcolloidal precursor sol sample even with a low amount of SDA, a highquality chabazite zeolite forms in an extremely short period of time.Samples 7-12 show that this phenomenon is not exclusive to silica bulkmodified with Al chlorohydrate and occurs with other arrangements(surface modified for example) or other aluminum bearing dopants.

TABLE 2 Beta Zeolite Nucleation Results Sample Crystallization SDA: # T(° C.)/t (hrs) Precursor Type Si Crystallinity % 14 140/24 Al surface0.5 Beta, 98 modified silica 15 140/24 Fumed silica + 0.5 Amorphous Alacetate blend 16 140/24 Silicic acid + 0.5 Amorphous Al acetate blend 17140/6  Al surface 0.5 Beta, 77 modified silica 18 140/3  Al surface 0.5Beta, 43 modified silica 19 140/12 Al surface 0.5 Beta, 54 modifiedsilica

Table 2 demonstrates that the phenomenon not only applies to thesynthesis of the chabazite but also applies to other zeolites such asbeta type zeolite. In this case tetraethylammonium SDA was used.Presumably the increase in kinetics and crystallinity of zeolites occurswith all types of SDA and with all modified colloidal silicaarrangements. Samples 15 and 16 utilized a mixture bearing silica anddissolved aluminum, but in which the aluminum and silicon did not startout modified within or along the colloidal sols and were instead freefloating within the carrier phase with no chemical bond between them.These samples did not form beta zeolite under these conditions. Incontrast, sample 14 shows that when using a modified precursor under theidentical conditions with identical amounts of silica, oxygen, andmetal, a 98% beta zeolite forms. Moreover, samples 17-19 show that inshorter periods of time beta zeolites also form.

While this invention may be embodied in many different forms, there aredescribed in detail herein specific preferred embodiments of theinvention. The present disclosure is an exemplification of theprinciples of the invention and is not intended to limit the inventionto the particular embodiments illustrated. All patents, patentapplications, scientific papers, and any other referenced materialsmentioned herein are incorporated by reference in their entirety.Furthermore, the invention encompasses any possible combination of someor all of the various embodiments mentioned herein, described hereinand/or incorporated herein. In addition the invention encompasses anypossible combination that also specifically excludes any one or some ofthe various embodiments mentioned herein, described herein and/orincorporated herein.

The above disclosure is intended to be illustrative and not exhaustive.This description will suggest many variations and alternatives to one ofordinary skill in this art. All these alternatives and variations areintended to be included within the scope of the claims where the term“comprising” means “including, but not limited to”. Those familiar withthe art may recognize other equivalents to the specific embodimentsdescribed herein which equivalents are also intended to be encompassedby the claims.

All ranges and parameters disclosed herein are understood to encompassany and all subranges subsumed therein, and every number between theendpoints. For example, a stated range of “1 to 10” should be consideredto include any and all subranges between (and inclusive of) the minimumvalue of 1 and the maximum value of 10; that is, all subranges beginningwith a minimum value of 1 or more, (e.g. 1 to 6.1), and ending with amaximum value of 10 or less, (e.g. 2.3 to 9.4, 3 to 8, 4 to 7), andfinally to each number 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 containedwithin the range. All percentages, ratios and proportions herein are byweight unless otherwise specified. Unless otherwise indicated hereinmolecular weight or MW refers to molecular weight as measured by weightaverage.

This completes the description of the preferred and alternateembodiments of the invention. Those skilled in the art may recognizeother equivalents to the specific embodiment described herein whichequivalents are intended to be encompassed by the claims attachedhereto.

1. A method of forming zeolites, the method comprising subjecting acolloidal silica sol modified with a metal bearing particle and in thepresence of an SDA to a temperature of at least 100° C. for a timeperiod of at least 0.1 hours and no more than 10 hours, wherein the SDAis a bromide, chloride, or hydroxide of an ammonium salt wherein theammonium group is selected from tetramethylammonium,tetrapropylammonium, tetraethylammonium, tetrabutylammonium,tetrahexylammonium, tetraoctylammonium, tributylmethylammonium,triethylmethylammonium, trimethylphenylammonium,methyltripropylammonium, dodecyltrimethylammonium,hexadecyltrimethylammonium, dimethyldodecylethylammonium,diethyldimethylammonium, or a combination thereof.
 2. The method ofclaim 1, wherein the metal bearing particle includes a metal which isone item selected from the group consisting of: an alkali metal, analkaline earth metal, a 1st row transition metal, a 2nd row transitionmetal, a lanthanide, aluminum, cerium, titanium, tin, zirconium, zinc,copper, nickel, molybdenum, iron, rhenium, vanadium, boron, and anycombination thereof.
 3. The method of claim 1, wherein the SDA isselected from the group consisting of: tetramethylammonium hydroxide,tetrapropylammonium hydroxide, tetraethylammonium hydroxide,tetrabutylammonium hydroxide, tetrahexylammonium hydroxide,tetraoctylammonium hydroxide, tributylmethylammonium hydroxide,triethylmethylammonium hydroxide, trimethylphenylammonium hydroxide,methyltripropylammonium hydroxide, dodecyltrimethylammonium hydroxide,hexadecyltrimethylammonium hydroxide, dimethyldodecylethylammoniumhydroxide, diethyldimethylammonium hydroxide, and any combinationthereof.
 4. The method of claim 1, wherein the composition has anS-Value which is at least 20% lower than if the same amount of silicaand metal were present in a non-doped form.
 5. The method of claim 1,wherein the formed zeolite has essentially the identical properties tothe reaction product of polymerized silicic acid doped with metal andreacted at a temperature of at least 170° C. for a time period of atleast 50 hours and no more than 100 hours.
 6. The method of claim 1,wherein the metal bearing particle is embedded within a droplet of thecolloidal silica.
 7. The method of claim 1, wherein the metal bearingparticle is a droplet of the colloidal silica having a metal coatingsurrounding at least a portion thereof.
 8. The method of claim 1,wherein the time period is no more than 4 hours and the zeolitecrystallinity is in excess of 80%.
 9. The method of claim 1, wherein theresulting zeolite has a higher crystallinity than an otherwise identicalprocess differing only in that the metal and silicon were in a non-dopedform.
 10. The method of claim 9, wherein the resulting zeolite has ahigher crystallinity than an otherwise identical process differing onlyin that at least 10% more SDA was used and the metal and silicon were ina non-doped form.
 11. The method of claim 1, wherein the resultingzeolite has a higher crystallinity than an otherwise identical processdiffering only in that the metal and silicon were in a non-colloidalform.
 12. The method of claim 1, wherein the resulting zeolite ischabazite.
 13. The method of claim 1, wherein the resulting zeolite isbeta.
 14. The method of claim 1, wherein at least 90% of the metalbearing particle is a species in either a tetrahedral or octahedralarrangement.
 15. The method of claim 1, wherein the modified sol has achemical shift of at least 5 ppm as measured using a tetramethylsilanereference relative to an unmodified sol in a solution containing themetal bearing particle in a dispersed form.
 16. The method of claim 14,wherein the tetrahedral and octahedral units comprise aluminum butanother metal is present within the colloid.
 17. A composition of mattercomprising a colloidal silica sol modified with a metal bearing particleand an SDA, wherein at least 90% of the metal in the metal bearingparticle is in either a tetrahedral or octahedral arrangement, andwherein the SDA is a bromide, chloride, or hydroxide of an ammonium saltwherein the ammonium group is selected from tetramethylammonium,tetrapropylammonium, tetraethylammonium, tetrabutylammonium,tetrahexylammonium, tetraoctylammonium, tributylmethylammonium,triethylmethylammonium, trimethylphenylammonium,methyltripropylammonium, dodecyltrimethylammonium,hexadecyltrimethylammonium, dimethyldodecylethylammonium,diethyldimethylammonium, or a combination thereof.
 18. The compositionof claim 17, wherein the metal bearing particle comprises aluminum. 19.The composition of claim 17, wherein the metal of the metal bearingparticle is in the form of a Keggin structure.